Suffix used to add impact in l33t speak. Its origins seem tied to orz, meaning that the affected person is somewhat pleading mercy to the action the author does (see shape and definition of orz).
A trip to a grocery store, convenience store, or gas station for the sole purpose of buying an excessive amount of junk food and sugary drinks, usually with friends. A chud run often happens late at night and ends with everyone involved hating themselves afterwards.